The invention herein resides generally in the art of bridge construction. More particularly, the present invention relates to bridges constructed from forms that are carried by or suspended from temporarily positioned beams.
There are two commonly-used methods for forming long-span concrete structures such as bridges, parking decks, building floors, structures within stadiums, and the like. These structures may be made by either using pre-cast pieces which are manufactured off-site, and then transported to the construction site and assembled. Alternatively, these structures can be manufactured by building the forms on site, pouring concrete into the forms and then removing the forms.
The pre-cast method utilizes standard or special forms which receive concrete or other structural building-type material. After an appropriate curing time, the form is opened and the piece is removed. Reinforcing members may be included in the form if desired. Utilizing such forms allows the manufacturer to efficiently build a large number of building components to a particular specification depending upon end-use. Although this method is effective, there are high costs involved in shipping and erecting the pre-cast pieces. Additionally, craning the large weight of pre-cast pieces into place adds significant extra cost to high-rise structures.
The other common method for forming long-span concrete structures is where the forms are assembled on site with the desired reinforcing structure. In some instances, significant site preparations are required. Next, the concrete is poured into the form, and after it has set, the forms are removed. This method is also costly inasmuch as the site must be properly prepared to accommodate the form and supporting structure and then the supporting structure must be torn down, cleaned and removed or reinstalled after completion of the concrete pour and setting thereof. Forming the concrete members in place is quite expensive for highly-engineered structures such as bridges, stadiums, and high-rise structures.
One method, which is disclosed in U.S. patent application Ser. No. 09/467,703, filed Dec. 20, 1999, which is incorporated herein by reference, discloses a method for constructing long-span concrete structures utilizing a unique method of pre-stressing the concrete used to form the bridge. This method discloses utilizing beams as supports for forming a beam form upon which a bridge surface is later disposed. Although this method is effective, additional preparation work for preparing the bridge surface is needed. This is especially cumbersome when the span is over water and the support structure must be placed along the length of the beam form.
Therefore, there is still a need to provide a method for in-situ bridge forming which is fast, reliable, and structurally sound.
In light of the foregoing, it is a first aspect of the present invention to provide a method for constructing a bridge utilizing in-situ forms carried by or suspended from I-beams.
It is thus an aspect of the present invention to provide a method for constructing a bridge in which a bridge form and a connected support structure are disposed over an area to be spanned by the bridge.
It is another aspect of the present invention to provide a method for constructing a bridge, as set forth above, wherein concrete is poured into the bridge forms and after setting, the support structure may be disconnected and removed from the bridge forms.
It is a further aspect of the present invention to provide a method for constructing a bridge, as set forth above, wherein variations of the bridge form and connected support structure are provided. In one variation, at least two beams may be placed in a substantially parallel relationship over the area and decking is placed between the beams to provide a bottom form between the beams. Concrete is then poured into the forms between the beams and after setting, the beams are removed. The formed concrete slabs may then be laterally moved together to complete the bridge structure. In a second variation of the present invention, cribbing may be placed on both sides of the area to be spanned and a cross-beam is set on the cribbing. At least two hanger beams are then placed in a parallel relationship on the cross-beams and over the area. These hanger beams carry support assemblies which carry the bridge forms used to receive the concrete. After the concrete has set, the support structure and hanger beams are removed to provide the desired bridge structure. In a third variation of the present invention, a bottom form may be placed across the abutments prior to placement of the at least two beams which are placed in a substantially parallel relationship over the area. The beams are then secured to the bottom form such that they remain parallel with one another, whereupon end forms may be attached to the bottom form and side forms may be detachably secured to the beams and extend beyond a peripheral edge provided thereby. Concrete is then poured into the formed cavities and, after it has set, the end forms and side forms are removed. Next, the beams are detached from the bottom forms and removed to leave a side cavity which is then filled with concrete to complete the bridge structure.
It is yet another aspect of the present invention to provide a method for constructing a bridge according to the first variation, wherein the parallel beams may be placed upon an abutment which may have notches for receiving the beams.
It is yet another aspect of the present invention to provide a method for constructing a bridge, as set forth above, wherein for the first variation shims are provided to support the beams upon the abutments, and wherein after the concrete has set, the shims are removed so as to transfer weight of the concrete from the beams to the abutments and allow removal of the beams.
It is still another aspect of the present invention to provide a method for constructing a bridge, as set forth above, wherein for the first variation each beam may be provided with a deflection shim along the length of its bottom cross-piece to compensate for the weight of the poured concrete and to facilitate withdrawal of the beams after the poured concrete has set.
It is still a further aspect of the present invention to provide a method for constructing a bridge, as set forth above, wherein for the first variation, the beams may be provided with a plurality of cross-holes that are alignable with the cross-holes of the other beams such that a cross-tie may be inserted therethrough and allow for lateral movement of the slabs after the beams are removed to enhance the structural strength of the completed bridge.
It is an additional aspect of the present invention to provide a method for constructing a bridge, as set forth above, wherein cross-braces may be installed across the beams as part of the support structure to stabilize the beams during pouring of the concrete.
It is still yet another aspect of the present invention to provide a method for constructing a bridge, wherein for the second variation, the hanger beams may be placed in a substantially parallel relationship over the area and may be supported by the cross-beams.
Yet a further aspect of the present invention is to provide a method for constructing a bridge, as set forth above, wherein for the second variation a plurality of support assemblies extend from the hanger beams.
It is another aspect of the present invention for the support assemblies to carry decking and end and side forms that receive the poured concrete. Additionally, the support assemblies include an inverted T-section, wherein one end of a J-hanger is connected to the hanger beam and the other end carries the inverted T-section.
It is still a further aspect of the present invention to allow for length adjustment of the hangers to selectively position the completed deck with respect to the abutments.
It is still yet a further aspect of the present invention to provide a method for constructing a bridge according to the second variation, wherein a trolley may be positionable between adjacent beams for the purpose of carrying decking to a desired position along the length of the beams and wherein use of the trolley may be repeated until the decking extends between the abutments.
It is another aspect of the present invention to provide a method for constructing a bridge according to the second variation, wherein after the decking and forms have been filled with concrete and the concrete has set, the shafts of the hangers are cut to allow removal of the hanger beams.
It is still an additional aspect of the present invention to provide a method for constructing a bridge, as set forth above, wherein the second variation may use a support assembly that includes a member with hangers connected thereto that is positioned substantially parallel with the cross-beams.
It is yet an additional aspect of the present invention to provide a method for constructing a bridge, as set forth above, wherein a trolley assembly may be used to put the members in place and then to use another trolley assembly to place decking and other form materials on the members. As in the other variation, after the concrete has been poured and set, the hanger shafts are cut so as to allow for removal of the hanger beams.
Another aspect of the present invention is to provide a method for constructing a bridge, as set forth above, wherein any of the variations may be pre-assembled near their final location to be spanned and wherein the connected support structure and the pre-assembled bridge structure may be coupled to a moveable counterweight which is then moved to a position over the area.
It is yet another aspect of the present invention to provide a method for constructing a bridge, as set forth above, wherein the movable counterweight is de-coupled from the preassembled bridge structure to allow for pouring of concrete into the forms. The support structure is then disconnected and removed.
It is an additional aspect of the present invention to provide a method for constructing a bridge, as set forth above, wherein the preassembled bridge form and support structure may be formed in half sections in either side of the area to be spanned. Each half section is then connected to a moveable counterweight and then positioned in place and connected to one another.
The foregoing and other aspects of the present invention, which shall become apparent as the detailed description proceeds, are achieved by a method for constructing a bridge, comprising the steps of disposing a bridge form and a connected support structure over an area to be spanned by the bridge, pouring concrete into the bridge form, and disconnecting and removing the support structure from the bridge form.
These and other aspects of the present invention, as well as the advantages thereof over existing prior art forms, which will become apparent from the description to follow, are accomplished by the improvements hereinafter described and claimed.